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Photonic crystal nanobeam cavities with high-quality factors are very sensitive to the changes of the dielectric properties of their surroundings. Utilizing this high sensitivity and by applying chemical functionalization, an ultrasensitive chemical sensor for gases based on a nanobeam cavity was demonstrated. A limit of detection of 1.5 parts-per-billion (ppb) in ambient conditions, determined from the noise level of the system, was achieved for nerve agent simulant methyl salicylate. The nanobeam cavity's nonlinear thermo-optical bistability is also utilized to realize a threshold detector for cumulative chemical exposure.

Nanoscale field emission devices promise many advantages over traditional solid-state devices including fast switching speeds, extreme operating temperatures, and radiation hardness. Despite this, practical circuits have long been hampered by the extreme requirements of nanoscale field emitters. Devices have required vacuum packaging, or extremely sharp emission points that are difficult to reproduce, or cannot be integrated on a single wafer with independent gating. We demonstrate CMOS compatible, integratable two- and three-terminal devices operating at near atmospheric pressures with high single tip currents at low voltages that can be used as building blocks for future circuits.

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Nanoscale field emission devices are promising candidates to design high-frequency electronics due to the lack of scattering in the vacuum channel that enables ballistic transport. In-plane devices are relatively easy to fabricate with current fabrication techniques and offer sub-fF capacitance. In this work, the characteristics of lateral gold multi-tip field emission arrays are studied. Vacuum gaps between the electrodes of 30 nm are fabricated, which allow < 10 V operation. The effect of number of emitting tips on measured current is investigated. By taking advantage of the strong non-linearity in the emission characteristic, frequency mixing in the MHz range is also demonstrated.